非必需氨基酸在人体蛋白质补充中的应用：一种估算方法。

Nonessential amino acid usage for protein replenishment in humans: a method of estimation.

机构信息

Department of Medicine, University of Padova, Padova, Italy.

出版信息

Am J Clin Nutr. 2019 Aug 1;110(2):255-264. doi: 10.1093/ajcn/nqz039.

DOI:10.1093/ajcn/nqz039

PMID:31187867

Abstract

BACKGROUND

Essential amino acids (EAAs) are key factors in determining dietary protein quality. Their RDAs have been estimated. However, although nonessential amino acids (NEAAs) are utilized for protein synthesis too, no estimates of their usage for body protein replenishment have been proposed so far.

OBJECTIVE

The aim of this study was to provide minimum, approximate estimates of NEAA usage for body protein replenishment/conservation in humans.

METHODS

A correlation between the pattern of both EAAs and NEAAs in body proteins, and their usage, was assumed. In order to reconstruct an "average" amino acid pattern/composition of total body proteins (as grams of amino acid per gram of protein), published data of relevant human organs/tissues (skeletal muscle, liver, kidney, gut, and collagen, making up ∼74% of total proteins) were retrieved. The (unknown) amino acid composition of residual proteins (∼26% of total proteins) was assumed to be the same as for the sum of the aforementioned organs excluding collagen. Using international EAA RDA values, an average ratio of EAA RDA to the calculated whole-body EAA composition was derived. This ratio was then used to back-calculate NEAA usage for protein replenishment. The data were calculated also using estimated organ/tissue amino acid turnover.

RESULTS

The individual ratios of World Health Organization/Food and Agriculture Organization/United Nations University RDA to EAA content ranged between 1.35 (phenylalanine + tyrosine) and 3.68 (leucine), with a mean ± SD value of 2.72 ± 0.81. In a reference 70-kg subject, calculated NEAA usage for body protein replenishment ranged from 0.73 g/d for asparagine to 3.61 g/d for proline. Use of amino acid turnover data yielded similar results. Total NEAA usage for body protein replenishment was ∼19 g/d (45% of total NEAA intake), whereas ∼24 g/d was used for other routes.

CONCLUSION

This method may provide indirect minimum estimates of the usage of NEAAs for body protein replacement in humans.

摘要

背景

必需氨基酸（EAA）是决定膳食蛋白质质量的关键因素。它们的 RDA 已经被估计出来了。然而，尽管非必需氨基酸（NEAA）也被用于蛋白质合成，但到目前为止，还没有提出关于它们用于补充身体蛋白质的使用量的估计。

目的

本研究的目的是为人体补充/维持身体蛋白质的 NEAA 使用量提供最低的、近似的估计值。

方法

假设 EAA 和 NEAA 在人体蛋白质中的模式与其使用之间存在相关性。为了重建“平均”的氨基酸模式/组成（即每克蛋白质中的克氨基酸），检索了相关人体器官/组织（骨骼肌、肝脏、肾脏、肠道和胶原蛋白，占总蛋白质的 74%）的已发表数据。剩余蛋白质（占总蛋白质的 26%）的（未知）氨基酸组成被假定为除胶原蛋白以外的上述器官总和的氨基酸组成。利用国际 EAA RDA 值，得出了 EAA RDA 与计算得出的全身 EAA 组成的平均比值。然后，使用该比值来反推用于蛋白质补充的 NEAA 使用量。数据还使用估计的器官/组织氨基酸周转率进行了计算。

结果

世界卫生组织/粮农组织/联合国大学 RDA 与 EAA 含量的个体比值在 1.35（苯丙氨酸+酪氨酸）和 3.68（亮氨酸）之间，平均值±标准差为 2.72±0.81。在一个 70 公斤的参考受试者中，计算得出的用于补充身体蛋白质的 NEAA 使用量范围为 0.73 克/天的天冬酰胺到 3.61 克/天的脯氨酸。使用氨基酸周转率数据得到了相似的结果。用于补充身体蛋白质的总 NEAA 使用量约为 19 克/天（占总 NEAA 摄入量的 45%），而用于其他途径的约为 24 克/天。